Fig. 1. Specific branchial Na⁺/K⁺-ATPase activity (V_spec) in carp acclimated for 8 weeks to water temperatures of 15, 22 or 29°C, and in 22°C-acclimated carp that had a minipump filled with vehicle or cortisol implanted for 7 days. Activity was assayed at optimal temperature (V_max; white bars) and at the acclimation temperature of the fish (V_apparent; grey bars). Values are means ± S.E.M. Asterisks indicate statistically significant differences among groups (*P<0.05; **P<0.01).